When I first made Negative Lab Pro, my focus was mainly on DSLR scanning… but there was a ton of interest in it from users with scanners (particularly for using it the RAW DNG scans that can be made in Vuescan and Silverfast), so I’ve added that support over time.
Here are a few reasons that scanner owners told me they were frustrated with using their scanning software to edit color negatives, and switched to Negative Lab Pro instead.
The “Edit > Scan > Wait” cycle sucks. Having to edit and adjust each image preview before capture is a frustrating way to be working with Color Negatives. It’s so much more efficient and more enjoyable to capture all of the data in the negative’s themselves, and then be able to convert and edit your negatives later in Negative Lab Pro.
Once you hit that “scan” button, you’re locked in to your edits… Most of the edits you make in scanning software are destructive… so if you are using the scan software to convert your negatives, those changes are getting locked in once you hit that “scan” button. From that point, you can only edit on top of the assumptions that have already been built in to the conversion (rather than working purely off the original unedited version). It’s sort of like working with a JPEG file from a digital camera rather than the original RAW file. Negative Lab Pro is a RAW, non-destructive workflow. You can alway go back and readjust your assumptions or even fully un-convert back to the original Negative. It just give you more flexibility and power in how you edit.
A lot of scanning software is outdated or difficult to use - This will obviously be based on personal preference, but most scanning software is quite old, or hasn’t changed in quite some time. I think Vuescan is actually one of the best when compared to other scanning software in this regard.
Not happy with the colors or tones from scanning software – especially for users who were looking for the look and feel of scans from a Lab scanner (like a Frontier or Noritsu), a lot of users were disappointed with the colors and tones they were getting out of their native software, and found they liked the results and control they got from Negative Lab Pro.
So that’s why I’ve continued to add support and improvements for working with traditional scanners (in addition to DSLR film scanners).
I hope that helps answer your question!